Are new engine oils safe for ageing cars?
The VLS urges workshops to consider the risks of using the latest engine oils in ageing customer vehicles.
The number of vehicles on UK roads is growing, but it’s also ageing. According to the latest European Automobile Manufacturers Association (ACEA) 2023 ‘Vehicles in Use’ report, there are 40.4 million vehicles on UK roads, including 5.2 million vans, trucks and buses. The average age of vans is 9.8 years, up from 7.8 in 2021. For trucks, the average age is now 11.6, up from 7.3 in 2021 and the average bus is now 16 years old, compared to 9.9 years in 2021.
The economic impact of COVID-19, automotive supply chain issues, uncertainty about electric vehicles and the future of the internal combustion engine, inflationary pressures and slow economic growth mean that business owners and fleet operators are holding onto their vehicles for longer than ever.
Harald Oosting, Chairman of industry trade body the Verification of Lubricant Specifications (VLS), commented: “On the one hand, this is good news for workshops. With older vehicles on the roads, there is more demand for servicing, repairs and MOTs. However, as cars age, some aspects of servicing, such as choosing the right engine oil, can become more complex.”
Engine technology has evolved significantly. To meet government requirements for reduced emissions and consumer needs for economy and performance, smaller engines are running at higher temperatures to maximise efficiency, power output and fuel economy. Longer oil drain intervals, taken together with smaller sumps and the need to minimise emissions, have created the need for less viscous, synthetic or semi-synthetic oils to provide the lubrication required in these challenging conditions.
But are these highly efficient, sometimes ultra-low viscosity lubricants suitable for the ageing vehicles being serviced in workshops? The latest formulations are specifically developed for the most modern engines. Traditionally, when newer oils were developed, some were designed to be ‘backwards compatible’. However, with an increasingly complex range of industry and OEM specifications, backwards compatibility cannot be assumed. Subtle yet important differences concerning viscosity characteristics and/or additive chemistries are reflected in specifications that must be acknowledged during regular servicing.
For example, Volvo VDS-5 is a new heavy duty fuel-efficient diesel engine oil specification with an SAE viscosity of 5W-30. Designed for in the latest 13L engines (Euro VI Step D), it is not backward compatible with previous Volvo Long Drain Specification fluids such as a Volvo VDS 4.5 SAE 10W-30 grade. The lower viscosity results in lower oil pressure, which could lead to multiple dashboard warning triggers. It is, however, expected to deliver over 0.5% fuel economy improvements versus 10W-30 oils.
Generally speaking, using the wrong oil risks damage to emission control systems, accelerated wear in gears and bearings and the formation of piston deposits, leading to increased maintenance costs. Left unchecked, it could lead to eventual engine failure, meaning higher maintenance costs for your customers and potential damage to your business’ reputation. If you put a low viscosity, low SAPS (Sulphated Ash, Phosphorous and Sulphur) oil in a vehicle requiring high levels of SAPS and viscosity, it may not offer the wear protection required. The additives for a lower SAPS oil will differ as well. Additives help to provide the performance characteristics of an engine oil, but modern lubricants are designed to deliver performance through a thinner, less viscous oil that might not be suitable for older cars.
It could be tempting to use cheaper oils to offset rising costs. However, the cheapest possible oil could be a full SAPS oil intended for older vehicles. This could have a negative impact on the exhaust emission system, poison the catalyst or block the Diesel or Gasoline Particulate Filters, reduce the overall efficiency and result in failure of the particulate filter or catalyst, both expensive to replace. Too much phosphorous from a high SAPS oil can also poison the Selective Catalyst Reduction units designed to control Nitrogen Oxide emissions. Short-term gain may lead to long-term pain for you and your customers.
For mechanics selecting oils for the vehicles in their workshops, online lubricant databases operated by most lubricant companies provide a recommendation as a starting point for the correct oil based on a vehicle’s registration. Technicians should verify this recommendation by direct reference to the vehicle manual and also the actual product claims in marketing literature, technical data sheets and product labelling provided by their supplier. Looking beyond the viscosity to specific performance claims such as the ACEA sequences and OEM standards should ensure that the lubricant is fit for purpose in that specific vehicle. Be careful with generic OEM claims such as ‘Suitable for Use’ without checking the necessary underpinning technical data that supports the claim.
If workshops are in any doubt about which oil to use for a particular vehicle, they should contact the vehicle manufacturer for assistance.
